1. Field of the Invention
This invention generally relates to carrier bags that are convertible to boxes and, more particularly, to closures for effectively maintaining the bags closed during carrying of objects placed within the bags.
2. Description of Related Art
It is known to convert a bag composed of paper or like sheet material into a box of parallelepiped shape by folding upper marginal portions or flaps of the bag inwardly over the open mouth of the bag and into mutual overlapping engagement so as to close the bag mouth. To maintain the bags closed, it is known, for example, from U.S. Pat. No. 2,992,768 and 3,447,736, to frictionally retain a string carrying handle in slits formed in the overlapping flaps. It is also known, from U.S. Pat. No. 2,532,778, to use snap fasteners. It is further known,from U.S. Pat. No. 875,224, to employ bendable tongues to keep overlapping box flaps together.
Although generally satisfactory for their intended purposes, the known containers in which bags are convertible into boxes have not proven to be altogether effective in maintaining the box closed under the weight of an object to be carried in the box. Experience has shown that some objects, particularly of heavy weight, sometimes cause the overlapping flaps to unfold and the box to collapse under the weight of the object. Thus, the aforementioned snap fasteners tend to unsnap; bent-over tongues tend to unbend; and string handles tend to pull out of their slits, when subjected to the weight of heavy objects. The resultant collapsed box with unfolded flaps was very unsightly, particularly when it is appreciated that the top of the box is its most conspicuous part. Also, an open bag was undesirable because it permitted rain, airborne dust and dirt to enter the box.